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To test whether the dose addition and independent action models can predict the combined toxicity of the mixtures of phenol and aniline derivatives, six phenolic and two aniline derivatives were selected as the test components. The inhibition toxicity of the derivatives and their mixtures to Vibrio qinghaiensis sp.-Q67 indicated that all dose-response relationships could be effectively described by the Weibull function with correlation coefficients greater than 0.99. The combined toxicity of two equivalent-effect concentration ratio mixtures and eight uniform design concentration ratio mixtures could be predicted successfully by the dose addition model within 95% confidence intervals. However, it was also well predicted by the independent action model, especially at lower concentrations.

a b s t r a c tThe interaction between endocrine disruptor phthalic acid esters (PAEs) and human serum albumin (HSA) was studied by fluorescence spectroscopy and molecular modeling methods. The efficiency of energy transfer and the distance between HSA and PAEs were calculated. The results showed that all of the four kinds of PAEs could quench the intrinsic fluorescence of the HSA, with the mechanisms of static quenching and non-radiative energy transfer. Molecular docking study and thermodynamic analysis revealed that the binding behavior was mainly governed by hydrophobic force. And the results of site marker competitive experiments and modeling method suggested that the four PAEs would mainly bind to the HSA in sub-domain IIIA, which demonstrated that the experimental results could coordinate with the theoretical results. Molecular dynamic simulation (MD) revealed that HSA did have a slight conformational change when it bound with PAEs. It also verified the greater stability of HSA-PAEs complex compared to free protein.

In this paper, a simple and sensitive approach for human immunoglobulin G (hIgG) detection is described based on nanoparticle surface energy transfer (NSET) from fluorescein isothiocyanate (FITC) to gold nanoparticles (GNPs). The assay consisted of polyclonal goat anti-IgG antibody labeled luminescent FITC as the donor and GNPs as the acceptor. In the initial stage, with the energy transfer from FITC to GNPs, the FITC fluorescence was effectively quenched. Upon the introduction of IgG, effective competitive binding to the polyclonal goat anti-IgG antibody labeled FITC occurred, which significantly hindered the NSET, and thus recovered the fluorescence of FITC. The change in fluorescent intensity produced a novel strategy for the detection of hIgG. The recovered fluorescence of FITC was linearly proportional to the concentration of hIgG in the range of 4.0 Â 10 À9 to 2.2 Â 10 À7 g mL À1 with a detection limit of 8.3 Â 10 À10 g mL À1 . This method was applied to the determination of hIgG in human serum samples via a standard addition method, and the recovery rate obtained was 98.7-105.0%.